Polybromo-cycloaliphatic ethers

ABSTRACT

A UNIQUE GROUP OF HIGH BOILING WATER INSOLUBLE POLYHALOALKYL AND CYCLOALKYL ETHERS IS DESCRIBED, ALL OF WHICH ARE USEFUL AS EXTERNAL PLASTICIZERS AND FLAME RETARDER FOR THERMOPLASTIC ORGANIC POLYMERS, SUCH AS POLYETHYLENE, POLYSTYRENE AND POLYMETHYLMETHACRYLATE. THESE PLASTICIZER/FLAME RETARDER COMPOSTIONS ARE ADVANTAGEOUSLY PRODUCED BY ADDING A SOLUTION OF HALOGEN. SUCH AS BROMINE, IN A LOWER ALIPHATIC ALCOHOL TO A MULTI-UNSATURATED ALIPHATIC OR CYCLOLIPHATIC HYDROCARBON AND THEN ADDING SUFFICIENT WATER TO THE REACTION MIXTURE TO SEPARATE THE DESIRED PRODUCTS AS AN INSOLUBLE LOWER LIQUID PHASE.

United States Patent 01 fice 3,5311 12 Patented Dec. 28, 1971 US. Cl. 260611 R 4 Claims ABSTRACT OF THE DISCLOSURE A unique group of high boiling water insoluble polyhaloalkyl and cycloalkyl ethers is described, all of which are useful as external plasticizers and flame retarders for thermoplastic organic polymers, such as polyethylene, polystyrene and polymethylmethacrylate.

These plasticizer/flame retarder compositions are advantageously produced by adding a solution of halogen, such as bromine, in a lower aliphatic alcohol to a multi-unsaturated aliphatic or cycloaliphatic hydrocarbon and then adding sufficient water to the reaction mixture to separate the desired product as an insoluble lower liquid phase.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to (A) a unique group of polyhaloalkyl ethers and cycloalkyl ethers containing from about 5 to about 28 carbon atoms and from 2 to 7 halogen substituents, preferably bromine, which possess high melting points and low water solubility, (B) processes for the production of such compounds by the reaction of a multiunsaturated aliphatic or cycloaliphatic hydrocarbon with halogen and a lower aliphatic alcohol and (C) plasticized self-extinguishing thermoplastic organic polymers containing such compounds.

(2) Description of the prior art The use of bromoalkanes and polybromoalkanes as flame retarders in thermoplastic organic polymers is well known. While many of these prior art compounds are effective for this purpose at low concentrations and possess a desirably high melting point and low water solubility, polymers containing these materials are often too brittle for low temperature applications. This condition can often be remedied by employing such brominated compound in conjunction with a conventional plasticizer, such as a phosphate ester. The presence of such multiple additives not only increases the cost of the polymer composition, but may, under severe conditions, also result in degradation of the polymeric chain induced by interaction or decomposition products of these additives.

SUMMARY It has now been discovered that thermoplastic polymers can be both plasticized and rendered flame retardant by the incorporation therein of a novel, highly stable polyhaloalkyl ether or cycloalkyl ether of the formula:

wherein X is a halogen group, R is a saturated aliphatic or cycloaliphatic hydrocarbon group containing from about 4 to about carbon atoms, R is an aliphatic or cycloaliphatic group, a is 2 to 7, b is 1 to 4, the ratio of a to b is at least 1 and the sum of a and b is an even integer from 4 to 8. It has also been found that such polyhaloalkyl ethers and cycloalkyl ethers can be ob tained in high yield and purity by reacting a multi-unsaturated aliphatic or cycloaliphatic hydrocarbon containing from about 4 to about 20 carbon atoms with a solution of halogen in a liquid aliphatic or cycloaliphatic alcohol and then adding sufficient water to the reaction mixture to separate the desired compound as an insoluble lower liquid phase.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As indicated above, the polyhaloalkyl ethers and cycloalkyl ethers of this invention, having the formula X R(OR) are stable, high boiling materials having low water solubility. These compounds, and particularly those in which the halogen is bromine, have been found to function effectively in low concentrations in thermoplastic organic polymers as external plasticizers and flame retarders. Because of their unique physical properties, these materials are highly resistant to being lost through leaching, vaporization or decomposition when incorporated in the thermoplastic polymer, thereby permitting the use of such polymer in applications where it is exposed to severe conditions of water, sunlight and temperature. These compounds are advantageously employed in quantities of from about 0.1% to about 10% by weight of the polymer. They have been found to be particularly effective in plasticizing and imparting flame retardancy to readily flammable hydrocarbon polymers such as polyethylene, polypropylene, polystyrene, high impact polystyrene and polybutadiene, as well as to other vinyl polymers such as polymethylmethacrylate, polyacrylamide, ABS or even the difficulty flammable polyvinyl chloride. In addition to their use in vinyl polymers, these compounds may be employed as external plasticizers and flame retarders in any other organic polymer, such as the polyamides, polyesters and polyurethanes.

Aliphatic compounds corresponding to the above formula in which R is a saturated aliphatic hydrocarbon group containing from about 8 to about 12 carbon atoms, R is a saturated aliphatic group containing from about 1 to about 8 carbon atoms, X is bromine group and the sum of a and b is an even integer from 4 to 6 represent a preferred group of compounds of this invention. Exemplary of such compounds are methoxy-tribromooctane, ethoxy-tribromooctane, ethoxy-pentabromo-methylheptane, ethylhexoxypentabromooctane, ethoxy-pentabromodecane, diethoxy-dibromooctane, diethoxy-tetrabromodecane and triethoxy-tribromodecane. The polybromoalkyl ethers in which R contains from 8 to 10 carbon atoms, b is 1 and the sum of a and b is 6 are particularly effective flame retardants.

Of the cycloaliphatic compounds of this invention, a preferred group is represented by the polybromocycloalkyl ethers of the above formula in which R is a saturated cycloaliphatic hydrocarbon group containing a 5 to 16 member carbocyclic ring. Examples of such compounds include methoxy-tribromocyclooctane, ethoxy-tribromocyclooctane, ethylhexoxy-tribromocyclodecane, ethoxypentabromocyclododecane, diethoxy-dibromocyclooctane, diethoxytetrabromocyclododecane and triethoxy tribrornocyclododecane. As in the case of the aliphatic compounds described above, maximum flame retardancy is possessed by those compounds in Which b is l. A particularly effective, and therefore preferred, group of cycloaliphatic compounds is that in which all of the bromine and alkoxy or cycloalkoxy groups are present as substituents on the carbocyclic ring (especially one containing 8 to 12 members), b is 1 and the sum of a and b is 4 or 6.

The compounds of this invention can be produced in high yield and purity by reacting a multi-unsaturated aliphatic or cycloaliphatic hydrocarbon containing from about 4 to about carbon atoms with a halogen, preferably bromine, in a reactive lower aliphatic or cycloaliphatic alcohol solvent, such as methanol, ethanol, cyclohexanol or 2-ethylhexanol. This reaction is advantageously conducted under substantially anhydrous conditions at a temperature of from about 10 C. to about C., preferably at about room temperature. Reaction temperatures above C. or below 10 C. are also operative; however there are few advantages to compensate for the low reaction rates or high halogen losses which often accompany normal pressure reactions conducted at these extreme temperatures.

In a preferred embodiment of this process, by-product formation is minimized by slowly adding the solvent solution of halogen to the unsaturated hydrocarbon, thereby maintaining less than a stoichiometric quantity of halogen in the reaction Zone during a major portion of the reaction period. The bulk of the by-products that are formed are insoluble in the reaction mixture and are advantageously removed by conventional means prior to the addition of sufficient water to effect total phase separation between the solvent and the polybromoalkyl ether or cycloalkyl ether product.

The relative proportions of mono and polyether products obtained can, to a limited degree, be controlled by the relative quantities of bromine and alcohol present during the reaction. In general, mono ether product formation is favored at higher mole ratios of bromine to alcohol, with increasing quantities of product containing more than one ether group being formed as this ratio is decreased.

The quality of reactive alcohol solvent that is employed may be varied over a wide range. Since a function of the alcohol is provide a mobile reaction mixture, as well as being a reactant, it is usually advantageous to employ a volume of alcohol that is at least as large and preferably several times as large as that of the unsaturated hydrocarbon.

Among the multi-unsaturated aliphatic or cycloaliphatic hydrocarbons which are suitable for use in this process to produce the polyhaloalkyl ethers and cycloalkyl ethers of this invention are 1,3-butadiene, isoprene, piperylene, 1,4- hexadiene, 1,7-octadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1,4 divinylcyclohexane, 4-vinyl-cyclohexene, 1.5-cyclooctadiene, 1,6-cyclodecadiene, 1,5-cyclododecadiene 4-methyl-1,3,6-heptatriene, 1,4,7-octatriene, 1,4,9- decatriene, 1,5,9-cyclododecatriene, 1,5,9-trimethyl-1,5,9- cyclododecatriene, 1,3,5,7-cyclooctatetraene and 1,5,9,l3- cyclohexadecatetraene.

The numerous advantages inherent in the practice of the instant invention will be apparent to those skilled in the art from an examination of the following examples.

EXAMPLE I A clean dry five liter flask equipped with a stirrer is charged with 3,000 grams of absolute ethanol and 250 grams of 1,5-cyclooctadiene. The contents of the flask is heated to 37 C. and 750 grams of bromine is added dropwise over a two-hour period. Stirring is continued for an additional five minutes and the entire reaction EXAMPLE II The procedure of Example I is repeated employing 125 grams of 1,5-cyc1ooctadiene and 375 grams of bromine, the bromine being introduced as a solution in 1,000 grams of absolute ethanol. Work up of the reaction mixture as in Example I yields two major fractions which are identified as ethoxy-tribromocyclooctane and diethoxy-dibromocyclooctane.

EXAMPLE III The procedure of Example II is repeated employing, in place of cyclooctadiene, 125 grams of 1,5,9-cyclododecatriene. Vacuum distillation of the liquid product yields three major fractions which are identified as ethoxy-pentabromocyclododecane, diethoxy-tetrabromocyclododecane and triethoxy-tribromocyclododecane.

EXAMPLE IV The procedure of Example 11 is repeated employing 110 grams of 1,4,9-decatriene in place of cyclooctadiene. Vacuum distillation of the liquid product yields three major fractions which are identified as ethoxy-pentabromodecane, diethoxy-tetrabromodecane and triethoxy-tribromodecane.

EXAMPLE V The procedure of Example I is repeated employing methanol in place of ethanol as the reaction solvent, yielding methoxy-tribromocyclooctane.

EXAMPLE VI A clean dry five liter flask equipped with a stirrer is charged with 3,000 grams of 2-ethylhexanol and 125 grams of 1,5-cyclooctadiene. The contents of the flask is then held at room temperature during the dropwise addition over a two-hour period of a solution of 375 grams of bromine in 1,000 grams of Z-ethylhexanol. Work up of the reaction mixture as in Example I yields both the tribromomonoether and the dibromodiether.

EXAMPLES VII-XIV In each of the examples in the following table, the designated flame retardant plasticizers and organic polymers are blended for thirty minutes in a double ribbon blender, extruded and pelletized. Test bars are then produced by injection molding and measurements made of impact strength at 0 C. and resistance to flame propagation. The samples are then immersed in water at C. for hours and the measurements of impact strength and flame resistance repeated. In no case is more than a minor difference detectable.

TABLE I Weight Weight additive polymer Example Additive (g.) Polymer VII Ethexy-tribromecyclooctane 2 H.D.polyethylene 98 VIII ..do 5 .do 95 IX Diethoxy-dibromoeyelooctane 3 Pelymethylmethacryla 97 X Ethoxy-pentabromodeeane 2 Polypropylene 98 XL- Ethoxy-pentabromoeyclododecan 2 de 98 XIL Diethoxy-tetrabromocyelndodecane 3 Polystyrene 97 XIIL Triethoxy-tribromocyclododecauo 2 Polyvinylehloride 98 XIV H Di(2-ethylhexoxy)-dibromocyci0oetane (0%) plus (2-ethylhexoxy)-tribre1uocyelooetane 2 ...de 9s I claim:

1. A compound of the formula Br -(O-R) wherein R is a saturated cycloaliphatic hydrocarbon group containing from five to sixteen carbon atoms, all of which are present in a single carbocyclic ring, and R is a saturated aliphatic hydrocarbon group containing from one to about eight carbon atoms, a is at least three, b is one and the sum of a and b is an even integer from four to eight.

2. A compound of claim 1 wherein all Br and OR groups are present as substituents on an eight to twelve member carbocyclic ring. 1

3. A compound of claim 1 wherein all Br and OR groups are present as substituents on a twelve member carbocyclic ring and the sum of a and b is six.

4. Alkoxy-tribromocyclooctane, wherein the alkoxy group contains from about one to about eight carbon atoms.

References Cited UNITED STATES PATENTS Harris et al 260-614 X Glickman 260614 Ladd et a1. 260614 X Copenhaver et al. 260614 Patrick 260-614 X Canterino et a1. 260-94] X England 260-611 X BERNARD HELFIN, Primary Examiner US. Cl. X.R.

26033.2 R, 45.7 R, 615 R, 614 R 

